U.S Pat. No. 4,063,505 discloses a threading apparatus with an endless belt used in a rotary printing press. The endless belt system includes an upper and a lower belt, and the web to be threaded is nipped between the two. The upper and lower belts are pressed together by rollers and are aligned with each other by mechanically inter-engaging parts thereof or magnetically. A partial web produced after lengthwise cutting can be threaded via turning bars.
This apparatus is costly because of the need for two belts. Devices to guide the two belts add to the expense. This guidance apparatus must be located outside of the area of the web. The turning bars have expensive rollers in this area. Also, in addition to the one lengthwise cutting apparatus normally used, a second one is necessary which initially cuts the partial web to be threaded to a wider width for the length of the threading section so that the partial web can reach the threading belts outside of the web area.